Table 2.

Principal characteristics of the in vitro studies testing glucosamine

Model	Concentration	Results	Reference
Glucosamine sulfate
Human OA chondrocytes	5-500 μM	Inhibition of PLA2 and collagenase in a lesser extent through PKC inhibition	[12]
Human OA chondrocytes stimulated with IL-1β	10-1,000 mg/L	Inhibition of NF-κB activation Inhibition of COX-2 expression and synthesis and PGE2 release	[17]
Human chondrocytes stimulated with IL-1β	10 mM	Influence of the proteomic profile	[20]
Human OA cartilage explants	5 mM	Inhibition of catabolic and anabolic gene expression Superiority over glucosamine hydrochloride in the same conditions	[25]
Human OA osteoblasts	200 μg/ml	Inhibition of pro-resorptive agents	[24]
Glucosamine hydrochloride
Transfected cell lines	10 mM	Inhibition of ADAMTS-5 expression and activity	[13]
Human OA synovium explants	0.5-5 mM	Induction of HA production No effect of N-acetylglucosamine	[22]
D(+)-Glucosamine
Rat chondrosarcoma cell line and	2-16 mM	Inhibition of aggrecanase-dependent cleavage	[11]
bovine cartilage explants
Rat chondrocytes stimulated with IL-1β g/L	1-4.5	Reversion of IL-1β deleterious effect on PG anabolism	[14]
Rat chondrocytes stimulated with IL-1β	4.5 g/L	Inhibition of NF-κB	[16]
Rat chondrocytes stimulated with IL-1β	20 mM	Inhibition of inflammatory cytokines, chemokines and growth factors Inhibition of MMPs and aggrecanase-1	[15]
Human synovial cells and chondrocytes	0.1-1.0 mM	Stimulation of HA and GAG production Stimulation of HA synthase activity No effect of N-acetylglucosamine	[21]
N-acetylglucosamine
Human chondrocytes stimulated with IL-1β	10 mM	Inhibition of iNOS, COX-2 and IL-6 expression	[18]
Human chondrocytes	5-20 mM	Increased synthesis of GAG and HA due to acceleration of facilitated glucose uptake Superiority over native glucosamine	[26]
Human chondrocytes (normal and OA) stimulated with IL-1β	2 mM	Prevention of the cytokine-induced demethylation of CpG site in the IL-1β promoter resulting in decreased expression of IL-1β	[19]

ADAMTS-5, a disintegrin and metalloproteinase with thrombospondin motifs 5; COX-2, cyclooxygenase-2; GAG, glycosaminoglycan; HA, hyaluronic acid; iNOS, inducible nitric oxide synthase; MMP, matrix metalloproteinase; OA, osteoarthritis; PG, proteoglycan; PKC, protein kinase C; PGE₂, prostaglandin E₂; PLA₂, phospholipase A₂.